Metrologia de instrumentos endodônticos por microscopia eletrônica de varredura e análise digital de imagens: uma proposta metodológica

A padronização para a fabricação de instrumentos endodônticos em aço inoxidável contribuiu para o desenvolvimento de novos aspectos geométricos. Surgiram propostas de alterações no desenho da haste helicoidal, da seção reta transversal, da ponta, da conicidade e do diâmetro na extremidade (D0). Concomitantemente, o emprego de ligas em Níquel-Titânio possibilitou a produção de instrumentos acionados a motor, largamente empregados hoje. A cada ano a indústria lança instrumentos com diversas modificações, sem, contudo, disponibilizar informações suficientes quanto às implicações clínicas destas modificações. Existe um crescente interesse no estudo dos diferentes aspectos geométricos e sua precisa metrologia. Tradicionalmente, a aferição de aspectos geométricos de instrumentos endodônticos é realizada visualmente através de microscopia ótica. Entretanto, esse procedimento visual é lento e subjetivo. Este trabalho propõe um novo método para a metrologia de instrumentos endodônticos baseado no microscópio eletrônico de varredura e na análise digital das imagens. A profundidade de campo do MEV permite obter a imagem de todo o relevo do instrumento endodôntico a uma distância de trabalho constante. Além disso, as imagens obtidas pelo detector de elétrons retro-espalhados possuem menos artefatos e sombras, tornando a obtenção e análise das imagens mais fáceis. Adicionalmente a análise das imagens permite formas de mensuração mais eficientes, com maior velocidade e qualidade. Um porta-amostras específico foi adaptado para obtenção das imagens dos instrumentos endodônticos. Ele é composto de um conector elétrico múltiplo com terminais parafusados de 12 pólos com 4 mm de diâmetro, numa base de alumínio coberta por discos de ouro. Os nichos do conector (terminais fêmeas) têm diâmetro apropriado (2,5 mm) para o encaixe dos instrumentos endodônticos. Outrossim, o posicionamento ordenado dos referidos instrumentos no conector elétrico permite a aquisição automatizada das imagens no MEV. Os alvos de ouro produzem, nas imagens de elétrons retro-espalhados, melhor contraste de número atômico entre o fundo em ouro e os instrumentos. No porta-amostras desenvolvido, os discos que compõem o fundo em ouro são na verdade, alvos do aparelho metalizador, comumente encontrados em laboratórios de MEV. Para cada instrumento, imagens de quatro a seis campos adjacentes de 100X de aumento são automaticamente obtidas para cobrir todo o comprimento do instrumento com a magnificação e resolução requeridas (3,12 m/pixel). As imagens obtidas são processadas e analisadas pelos programas Axiovision e KS400. Primeiro elas são dispostas num campo único estendido de cada instrumento por um procedimento de alinhamento semi-automático baseado na inter-relação com o Axiovision. Então a imagem de cada instrumento passa por uma rotina automatizada de análise de imagens no KS400. A rotina segue uma sequência padrão: pré-processamento, segmentação, pós-processamento e mensuração dos aspectos geométricos.

Aspects of the washout of salmonid eggs. 6. Information on gravel composition , redd sites, the dimensions of redds and the depth of egg burial

Sampling was concentrated on the North Moor region and the series of ditches which drained this area to the Bristol Channel. Although most ditches were not deep the mud substratum precluded sampling from within the habitat. All samples were taken with a pond net from the banks. Efforts were made to sample each part of the habitat although in some ditches the macrophyte growth was so intense as to make sampling difficult particularly of the sediments. Organisms were identified on the 10 sampling sites.

Tunable focal depth of an apodized focusing optical system

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Tunable focal depth of an apodized focusing optical system

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Feedback on the Rate and Depth of Chest Compressions during Cardiopulmonary Resuscitation Using Only Accelerometers

Background Quality of cardiopulmonary resuscitation (CPR) is key to increase survival from cardiac arrest. Providing chest compressions with adequate rate and depth is difficult even for well-trained rescuers. The use of real-time feedback devices is intended to contribute to enhance chest compression quality. These devices are typically based on the double integration of the acceleration to obtain the chest displacement during compressions. The integration process is inherently unstable and leads to important errors unless boundary conditions are applied for each compression cycle. Commercial solutions use additional reference signals to establish these conditions, requiring additional sensors. Our aim was to study the accuracy of three methods based solely on the acceleration signal to provide feedback on the compression rate and depth. Materials and Methods We simulated a CPR scenario with several volunteers grouped in couples providing chest compressions on a resuscitation manikin. Different target rates (80, 100, 120, and 140 compressions per minute) and a target depth of at least 50 mm were indicated. The manikin was equipped with a displacement sensor. The accelerometer was placed between the rescuer's hands and the manikin's chest. We designed three alternatives to direct integration based on different principles (linear filtering, analysis of velocity, and spectral analysis of acceleration). We evaluated their accuracy by comparing the estimated depth and rate with the values obtained from the reference displacement sensor. Results The median (IQR) percent error was 5.9% (2.8-10.3), 6.3% (2.9-11.3), and 2.5% (1.2-4.4) for depth and 1.7% (0.0-2.3), 0.0% (0.0-2.0), and 0.9% (0.4-1.6) for rate, respectively. Depth accuracy depended on the target rate (p < 0.001) and on the rescuer couple (p < 0.001) within each method. Conclusions Accurate feedback on chest compression depth and rate during CPR is possible using exclusively the chest acceleration signal. The algorithm based on spectral analysis showed the best performance. Despite these encouraging results, further research should be conducted to asses the performance of these algorithms with clinical data.

Evaluation of the In Situ Ichthyoplankton Imaging System (ISIIS): comparison with the traditional (bongo net) sampler

Plankton and larval fish sampling programs often are limited by a balance between sampling frequency (for precision) and costs. Advancements in sampling techniques hold the potential to add considerable efficiency and, therefore, add sampling frequency to improve precision. We compare a newly developed plankton imaging system, In Situ Ichthyoplankton Imaging System (ISIIS), with a bongo sampler, which is a traditional plankton sampling gear developed in the 1960s. Comparative sampling was conducted along 2 transects ~30–40 km long. Over 2 days, we completed 36 ISIIS tow-yo undulations and 11 bongo oblique tows, each from the surface to within 10 m of the seafloor. Overall, the 2 gears detected comparable numbers of larval fishes, representing similar taxonomic compositions, although larvae captured with the bongo were capable of being identified to lower taxonomic levels, especially larvae in the small (<5 mm), preflexion stages. Size distributions of the sampled larval fishes differed considerably between these 2 sampling methods, with the size range and mean size of larval fishes larger with ISIIS than with the bongo sampler. The high frequency and fine spatial scale of ISIIS allow it to add considerable sampling precision (i.e., more vertical sections) to plankton surveys. Improvements in the ISIIS technology (including greater depth of field and image resolution) should also increase taxonomic resolution and decrease processing time. When coupled with appropriate net sampling (for the purpose of collecting and verifying the identification of biological samples), the use of ISIIS could improve overall survey design and simultaneously provide detailed, process-oriented information for fisheries scientists and oceanographers.